Patent GB-841283-A (GB)
Title: Inventory systems using magnetic storage of inventory items
IPC: H02B1/044
Filed: 1956-12-17
Abstract: 841,283. Digital electric calculating-apparatus; reservation of seats &c. TELEREGISTER CORPORATION. Dec. 17, 1956, No. 38472/56. Classes 106 (1) and 106 (3). In an electrical information storage system in which code signals identifying different items of information and signals representing the numerical values of the items are stored at a central station in first and second sections of a magnetic storage unit, in response to message code signals from a remote station a numerical quantity is added to or subtracted from each of the values of a desired group of items, and means for determining whether each of the new values obtained is equal to or greater, or is less, than a predetermined limiting value control the production of answer-back signals. General.-The aircraft booking system described comprises a magnetic drum 12, Fig. 2, on which are stored inventory balances indicating numbers of seats available on different flights or legs of flights. The circuitry for reading out, altering and writing the balances is controlled by signals on cable 8 from local key-sets 1, 2 and 3, Fig. 1, or by local transceivers 4 (only one shown) which store temporarily, e.g. on perforated tape or relays, signals received over line connector 5 from remote key-sets 6, a master seeker 7 allowing only one key-set to be effective at a time. Each key-set includes code-notched designation plates for selecting different groups of flight or leg inventories, keys for selecting the date, number of seats and the kind of " order " or operation required, and indicating lamps; a Check lamp is lit if an order can be completed and a Reject lamp remains unlit if the order cannot be completed or if an error has been made. The key-sets comprise agent's sets 1 on which only certain orders can be effected, a master set 3, and a special set 2 in the control tower for checking inventory balances before take-off of plane. For each kind of order (described separately below) a cycle of operations (called " Cycle I ") is effected in which a group of up to eight inventory storage positions are addressed in turn each during two drum revolutions. For orders in which an inventory balance has to be altered in adder/subtractor 42, due to a sale or cancellation, Cycle I is followed by Cycle II in which each balance is dealt with in three drum revolutions. The sequence of operations during both types of cycle is controlled by programming unit 34 which includes a 2-stage binary counter for marking the drum revolutions (Fig. 6, not shown). Examples are given of electronic circuit components, comprising mainly pentodes and double triodes which may be built up into standard units, the circuit elements comprising bi-stable and monostable flip-flop circuits, coincidence gates and mixers. Magnetic drum; address selection.-The drum 12, Fig. 2, has five synchronizing channels 19 which supply respectively 1, 16, 96, 960, and 1024 pulses per revolution to conductors 1 to 5 of cable 20. The inventory balances comprise 7-digit binary numbers stored in parallel on channels 26; one set of 7 channels are provided for each of the next 10 days, and 2 further channels for indicating availability of seats (without giving balances) on " X " (ordinary) or " Z " (holiday) days beyond the 10-day period. The required channel set or further channel is selected, in accordance with the date set up on the operative key-set, through decoder 9, and plug-board 10 (changed from day to day) whose output energizes one of 12 relays in selector unit 11. Each channel 26 comprises 1024 binary positions, and the 10-bit arc addresses for these channels are stored in serial form on 21 channels 13, 96 addresses being stored on each channel. The key-set code-plate supplies a 9-bit signal of which 5 bits are sent to relay selector 14 to select one of the address channels, and 4 bits operate group selection relays 22 to select a group of 8 addresses on the selected channel. An 8-stage ring 32, stepped on by pulses from unit 34, with output encoder 30, cause the 8 addresses to be dealt with in turn. When the output of scale-of-16 binary counter 21, which is stepped by the 16/R pulses on conductor 2 (comprising 12 spaced pulses and 4 rapid counter reset pulses), agrees with the output of unit 22, a comparator 18 sends a signal to a further comparator 23 which, when the output of a scale-of-8 counter 24, stepped on by pulses 96/R on conductor 3, agrees with the output of encoder 30, in turn supplies a signal via lock or gate 33, opened by unit 34 during the 1st revolution of a cycle step, to gate 16 whereby the required address is read out and entered serially in 10-stage shift register 17 which is stepped by the 960/R pulses on conductor 4. During the 2nd revolution of a cycle step, when the output of 10-stage binary counter 38, which is stepped by the 1024/R pulses on conductor 5, agrees with the shift register setting, a signal is applied via lock 28 to a 7-stage register 40 to cause the required inventory balance to be set up thereon. The stages of ring 32 are each controlled by a relay in group 31; where an order requires only some of the 8 addresses in a group only the relays corresponding to these addresses are energized, the ring stages corresponding to de-energized relays being skipped. Adder / subtractor.-The stored inventory balance in register 40, Figs. 2 and 7, and a number from the operative key-set stored in relays 701 are applied over lines B, D to the 7 stages 2<SP>0</SP>-2<SP>6</SP> of a parallel binary adder (earth and negative potential representing " 1 " and " 0 " respectively). With relays 702, 705 deenergized as shown, earth is applied to bus 708 and negative potential to bus 707 to cause the number from the key-set to be entered in complementary form, and " 1 " is entered into carry input C 1  of the first stage, to effect subtraction. The carry output C 2  from the last stage 2<SP>6</SP> is applied to line 54 to provide a Check/Reject signal, the signals for the 8 addresses in a group being stored in the 8 stages of a distributive storage unit 43 from which they are returned via answer relays 44 to the lamps on the key-set. Each adder stage comprises two groups of three pentodes U, V, Y and W, X, Z, Fig. 8, and cathode follower output triodes E, F. Owing to the screen grid to suppressor grid cross-coupling of pentodes U and V, point A in their common anode circuit is at a relatively high or low potential according to whether the input digits at B and D, applied to the control grids, are the same or different; if either digit is " 1," the screen grid of U or V is lowered in potential by conduction thereto and cuts off conduction in pentode Y. The group W, X, Z respond similarly to the input from A and carry input C 2 . If the anode potential of W and X is relatively high, a " 1 " sum output is produced at S, and if the anode potential of Y and Z is high (both tubes cut off), a " 1 " carry output is produced at C 2 . Kinds of operation or orders.-The ten different orders are described below. Orders (2) to (4) involve Cycle II as well as Cycle I, and orders (4) to (8) and (10) cannot be effected on an agent's key-set. (1) Availability inquiry.-The full 16 revolutions of Cycle I are performed and during each 2nd or even revolution, the required number of seats set up from the key-set in relays 701, Fig. 7, is subtracted from the inventory balance read out and an answer signal Reject or Check obtained according to whether the difference is negative or not. (2) Selling a seat reservation.-The Cycle I operation is similar to that in an availability enquiry but may be restricted to cover only those inventory balances (in a group of 8) involved in the reservation. Provided adequate balances are found, the unit 34 proceeds to Cycle II in which the relevant balances are again addressed and read out as in Cycle I, but during each 3rd revolution, the signal from comparator 39, Fig. 2, is applied via lock 46 to seven gate amplifiers 45 to cause the difference computed in 42 to be written on the drum as the new balance. (3) Limited cancel order.-For this order, relays 703, 702 and 705, Fig. 7, are energized, to cause a number to be added to an inventory balance provided the latter is greater than zero; if the balance is zero, the agent refers the cancellation to the master agent who keeps a waiting list. During Cycle I, unit 34 supplies a positive bias over line 652 to the control grids of tubes 710, 712. Triode 712 conducts and supplies earth potential from its cathode through contacts 703c, 702b to bus 708, and contacts 702a supply earth potential to bus 707, whereby " 1 " is entered at input D in every stage of the adder. If the inventory balance entered at B is greater than zero, a carry output of " 1 " (positive signal) will be obtained from C 2  of stage 2<SP>6</SP> which is passed via contacts 703a to the control grid of tube 709. Pentodes 709, 710 form a coincidence circuit similar to U, V, Fig. 8, so that a positive anode output is obtained which is applied via cathode follower 711 and contacts 703b to line 54 to provide a Check signal which allows the unit 34 to proceed to Cycle II. During the following Cycle II, when the positive signal is removed from 652, the carry output from stage 2<SP>6</SP> (normally " 0 ") is inverted; and the number of seats to be cancelled, entered on relays 701, is added to the selected inventory balance and the new balance is recorded on the drum. (4) Unlimited cancel order.-This is similar to order (3) except that the test of the balance in Cycle I is omitted. Relay 704 is energized, which opens a contact in line 652 and closes a contact to energize relays 703, 702, 705. (5) Read-out of inventory balance.-This is effected in the same manner as an availability inquiry, but a number of seats is not entered so that none of relays 701 is energized. Thus zero is subtracted from the inventory balance, and the result on li